Accidental Upskirts Voyeur:

Upskirt is a slang term usually referring to up skirt photography, images of the view up a woman's skirt (as seen from underneath), including shots of a woman's underwear, or exposing her vulva or buttocks. While these images may be captured consensually, many viewers seek upskirt images taken surreptitiously (and presumably without the subject's consent). The creation and viewing of this type of upskirt are considered forms of voyeurism.